Machining operations often require clamps to hold a workpiece stationary during machining operations. Manually operated mechanical clamps have been used in the past for this purpose. More recently, manually controlled, electrical, pneumatic and hydraulically actuated clamps have been developed. While clamps can be electrical or mechanical, most modern clamps are pneumatically or hydraulically actuated. Still more recently, in order to accommodate modem machining operations, programmable clamps have been developed. Programmable clamps are designed for rapid movement between a clamped position and an unclamped position. The actuation of programmable clamps may be controlled by a computer or similar controller to permit the actuation of the clamp between a clamped and unclamped position without direct human intervention. Manual manipulations required by manually operated clamps are avoided, labor costs are reduced, and manufacturing times are decreased.
Unfortunately, existing manually controlled and programmable clamps are not without their problems. For instance, as a machining device machines a workpiece into a desired shape, the machining device may have to be positioned in or pass through a location occupied by a clamp. In order to avoid conflict, the clamp must be disengaged and displaced from the workpiece to allow access to the area by the machining device, causing significant increases in manufacturing cost and time.
One previously developed solution to the foregoing disengagement problem is the swing clamp. A swing clamp has a clamp arm that is rotated 90 degrees as the clamp arm is moved from a clamped position to an unclamped position, thereby partially displacing the clamp arm from the workpiece. Thus swing clamps permit some additional access to a work piece in the vicinity of such clamps. However, previously developed swing clamps are not without their problems. For instance, the clamp arms of previously developed swing clamps rise above the workpiece when moving to the unclamped position and rotating by 90 degrees. After rotation, the arms remain raised. This is often undesirable because a machining device having a part or component that extends horizontally outward from the cutting tool of the machining device may impact the raised clamp arm as the machining device works in the vicinity of the workpiece previously engaged by the clamp arm. Thus previously developed swing clamps can interfere with machining operations and potentially cause damage, if the machining device impacts a raised clamp arm.
Thus there exists a need for a swing clamp having an unclamped position such that no part of the swing clamp will interfere with machining operations in the vicinity of the clamp. Further, a need exists not only for a swing clamp that allows increased access of a machining device to a workpiece in the vicinity of the clamp, but is also economical to manufacture and has a high degree of reliability.